Strictly Come Dancing (often shortened to just "Strictly") is of course a very popular reality TV show featuring C-list celebrities taking on ballroom dancing. It first aired on BBC1 on 15th May 2004 and it is a staple of the Autumn Saturday night schedule. It is currently hosted by Tess Daly & Claudia Winkleman. There is short of content from the first 4 series that is available to watch online.
Content of the first 4 series are hard to find online, and is considered to be lost media. However, Series 1, Episode 1 was uploaded to Vimeo in 2016. YouTuber and dance enthusiast Antony Palmer has uploaded Series 2, Episode 1 titled "STRICTLY COME DANCING 2001" (even though the talent contest didn't exist back then), Series 3, Episode 10a (2005 final performances), Series 3, Episode 10b (2005 final results), Series 4, Episode 5 (2006 Week 5) & Series 4, Episode 12 (2006 final). The 2005 final results were uploaded by YouTuber randomVHStat in full. The 2 finals that were uploaded by Antony Palmer aren't full episodes, just excerpts; however, S4E5 isn't playable as it had been blocked by the BBC. Other than that, there isn't anymore full episodes between Series 1-4, only focusing on recent years as per usual.
Clips that are available online
Minor YouTuber Flimango & Chuck had created a playlist entitled "Strictly clips that are on YouTube", consisting of clips of individual dances and interviews from Series 1 & 2.